Who do I ask for a reference after a layoff?

The company closed and I am not sure how to reach former colleagues. It has been a long 18 weeks. I have one former client who liked my work. How do you ask politely?

Thanks for writing this out. I went through something close to it 6 months ago, and it settled down once I kept a simple log of every call and form.

I kept a note of my results so my references could be specific. They appreciated it.